Commercial and residential building security systems are widely used to deter theft of valuables, and to create a greater sense of security for the building occupants. A conventional building security system may include a central alarm controller and a plurality of building sensors connected to the controller. The building sensors may include switches on exterior doors and windows, as well as motion sensors or detectors inside and outside the building. An alarm siren, security lights, etc. may be activated responsive to the alarm controller detecting an intrusion based upon a triggered sensor and when the alarm controller is in the armed mode.
A building security system typically requires a way to move the alarm controller to a disarmed mode so that people can freely enter and exit the building without triggering an alarm. More complicated commercial systems may have computers located in security control centers that monitor access points. Such complicated systems may also include a plurality of magnetic card readers, for example, that grant a card bearer access if the code on the card matches a previously learned code of the system.
Many newer residential security systems include a more basic controller and building sensors. In addition, such residential systems may also include one or more remote transmitters, similar to the ubiquitous garage door opener, for switching the controller from the armed to disarmed state as the user approaches his residence.
Unfortunately, little attention has been paid to the details of the security that may be compromised by such remote transmitters. More particularly, a conventional home security transmitter typically generates a unique code; however, a would-be thief may cause the alarm controller to enter a learning mode and learn a new remote transmitter without the owner's knowledge. Accordingly, the thief can then return when the owner is absent and disarm the security system.